from StringIO import StringIO
import xhtml2pdf.pisa as pisa

html_data = '<b>your HTML data</b>'
html_data = html_data.encode('utf8')
html_data = StringIO(html_data)

output = StringIO()
pisa.log.setLevel('WARNING') #suppress debug log output
pdf = pisa.CreatePDF(
    html_data,
    output,
    encoding='utf-8',
    )

pdf_data = pdf.dest.getvalue()